Seat Heating, Basic Function - GF91.30-P-9900A
Model all (CAR)
with code 401 (Climatized front seats)
Model all (CAR)
with code 402 (Rear seat climate control)
Model all (CAR)
with code 872 (Left and right rear seat heating)
Model all (CAR)
with code 873 (Left and right driver's seat heating)
Model all (CAR)
with code 886 (Seat heater for 3rd seat row)
Model all (CAR)
with code 902 (Seat heater Plus for driver and front passenger)
Model all (CAR)
with code 903 (Rear comfort seat heating)
Overview:
This document contains information on:
- General
- Function requirements
- Front seat heater control
- Seat heating control in rear passenger compartment
- Manual switching on and off:
- Reduced heating output with multiple activation.
- Reduced heating output in ECO drive program.
- Additional seat heater Plus functions
- Actuation by other systems
General
The seat heating has the task of increasing the temperature of the seat cushion or seat backrest. The seat heating creates a more pleasant climate for vehicle occupants at low temperatures. The seat heating is performed via integrated heating elements in the seats.
Function requirements
- Circuit 15 or circuit 15R ON
- Only for front passenger seat heating:
Front passenger seat belt buckle contact (for approx. 15 minutes after change of circuit)
Front seat heater control
Depending on the equipment installed, one of the following control units actuates the seat heating:
Overview of front seats seat heating control
| Installed control units/position of seat heating | Driver's seat heating | Front passenger seat heating |
|---|---|---|
| Without seat heating Plus | ||
| Without driver's seat control unit Without front passenger seat control unit | Seat climate control, control unit | Seat climate control, control unit |
| With driver's seat control unit Without front passenger seat control unit |
Driver seat control unit | Driver seat control unit |
| With driver's seat control unit With front passenger seat control unit |
Driver seat control unit | Front passenger seat control unit |
| With seat heating Plus | Driver seat heater control unit (seat surface and seat backrest center section) and driver seat control unit (seat side bolsters) or Driver seat control unit |
Front passenger seat heater control unit (seat surface and seat backrest center section) and front passenger seat control unit (seat side bolsters) or Front passenger seat control unit |
Seat heating control in rear passenger compartment
Control of the seat heater is dependent on the equipment installed:
- If the rear seat is equipped with a seat control unit, it controls the seat heating.
- On rear seats without the seat control unit, a seat heater control unit is installed.
- With seat heating Plus, the seat control unit is often supported by an additional seat heater control unit.
Manual switching on and off:
The seat climate control switch group is installed in the doors or on the side wall of the respective side of the vehicle. The seat climate control switch group records the control signals via the seat heater button and sends them to the control system.
The heating output can set to 3 different levels. The actuation of the heating elements is performed by means of pulse width modulation (PWM) and thus enables actuation in 3 intensity levels (100 %/65 %/35 % power).
Reduced heating output in ECO drive program
If the ECO drive program is activated, the seat heating switches to a mode to reduce the operating current. This is done by means of reduced pulse-width modulated signals. The control system multiplies the individual output levels of the pulse width modulated signals by an ECO factor and thus reduces the heating output.
If the ECO drive program is deactivated, the seat heating automatically returns to the normal mode. On vehicles with seat heating Plus, this continues to regulate to the specified temperature, but with reduced PWM values at the output of the actuating control unit.
The control system sends the stage setting of the seat heating back to the seat climate control switch group. This actuates the LEDs in the seat heating button accordingly.
The heating output of the individual stages is also adjusted depending on the outside temperature. The heating output settings of the respective heating levels can be adjusted via the diagnostic tester.
Depending on the equipment, it is also possible to operate the seat heating in the rear passenger compartment via the vehicle's own tablet PC.
Reduced heating output with multiple activation
If the seat heating is selected again with the same circuit status, the seat heating actuates heating level 3 at only 90 % of the heating output.
It is possible to adjust the ECO factors using the diagnostic tester.
Additional seat heater Plus functions
Additional temperature sensors are installed in the seat heating mats. To monitor the seat heating, the seat heating control reads in the signals from the corresponding heater pad temperature sensors directly and evaluates them. In line with this data and the set heating level, the seat heating Plus actuates the heater pads.
In addition, actuation is carried out depending on the vehicle interior temperature. This enables faster heating to be achieved. The lower the vehicle interior temperature, the faster the seat heating Plus heats up the heater pads.
Actuation by other systems
For actuation by other systems, the function requirement for circuit 15 or 15R ON does not apply. With circuit 30t, the other systems can also activate the seat heating.
The seat heating can also be actuated by the following systems:
- Pre-air conditioning
- Revitalization
- Massage programs of multicontour seats
| Function schematics | |||
|---|---|---|---|
| Function schematic for actuating front seat heating | Model 118, 177, 247 with code 401 (Climatized front seats) Model 118, 177, 247 with code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97A | |
| Model 167 with code 401 (Climatized front seats) except code 902 (Seat heater Plus for driver and front passenger) Model 167 with code 873 (Left and right driver's seat heating) except code 902 (Seat heater Plus for driver and front passenger) | PE91.30-P-2502-97B | ||
| Model 167 with code 902 (Seat heater Plus for driver and front passenger) except code 401 (Climatized front seats) except code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97C | ||
| Model 293 with code 401 (Climatized front seats) Model 293 with code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97D | ||
| Function schematic for actuating rear seat heating | Model 167 with code 872 (Left and right rear seat heating) except code 886 (Seat heater for 3rd seat row) | PE91.30-P-2503-97A | |
| Model 167 with code 886 (Seat heater for 3rd seat row) | PE91.30-P-2503-97B | ||
| Model 167 with code 903 (Rear comfort seat heating) except code 872 (Left and right rear seat heating) except code 886 (Seat heater for 3rd seat row) | PE91.30-P-2503-97H | ||
| Model 293 with code 872 (Left and right rear seat heating) | PE91.30-P-2503-97C | ||
| Further basic functions | |||
| Seat climate control timer-control led shutoff, basic function | GF91.30-P-1000A | ||
| Seat climate control automatic shutoff, basic function | GF91.30-P-1001A | ||
| Control units | |||
| Seat control unit, basic function | Vehicles with seat heating and electrical seat adjustment at front, vehicles with seat heating and electrical seat adjustment in rear passenger compartment | GF91.29-P-9890A | |
| Seat climate control unit, basic function | Vehicles with seat heater and without electrical seat adjustment, vehicles with code 902 (Seat heater plus for driver and front passenger), vehicles with code 903 (Seat heater plus for rear outer seats) | GF91.30-P-9891A | |
| Components | |||
| Tablet cradle electric controller unit, basic function | Vehicles with code 447 (Touchscreen in rear passenger compartment (rear touchscreen)) and seat heating in rear passenger compartment | GF54.21-P-2007A |